Transcript for Two American Astronauts Will Take Another Spacewalk to Make Repairs on Cooling System

200 miles above the earth tonight they are preparing for a christmas eve mission now, a space walk after real concern over one of the space suits. This picture holding the clue tonight, a veteran astronaut revealing his feet were suddenly very cold. You'll hear his voice tonight. It was a red flag for him and mission control. Have they fixed it? Here tonight abc's ryan owens from houston. Reporter: The movie gravity has given millions the chance to sweat out a space walk but there is no need to rely on hollywood for drama this christmas eve. My toes are quite cold. Tomorrow morning american astronauts will step out of the space station to finish what they started this weekend, replacing this critical cooling pump. I know you trained for it, but is it scary when you are up there and there is nothing else? It is scary. It's a matter of just managing that fear. Reporter: Adding to that fear, those aging space suits. Astronauts spent today inspecting them. In july an italian space walker nearly drowned when water leaked into his helmet. Saturday another problem. Very very cold. Reporter: Tomorrow they hope to finish the job. Christmas morning we find a new pump module? Reporter: And you thought your holidays were stressful. We'll be watching tomorrow. Back on earth tonight and into the firestorm after

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